Question

我有以下查询可以正常工作：

SELECT c.cust_id, c.cust_type_cd, c.city, count(*) as `count`
FROM customer c
INNER JOIN account a
    ON a.cust_id = c.cust_id
GROUP BY c.cust_id
HAVING `count` = 2;

结果：

+---------+--------------+---------+-------+
| cust_id | cust_type_cd | city    | count |
+---------+--------------+---------+-------+
|       2 | I            | Woburn  |     2 |
|       3 | I            | Quincy  |     2 |
|       6 | I            | Waltham |     2 |
|       8 | I            | Salem   |     2 |
|      10 | B            | Salem   |     2 |
+---------+--------------+---------+-------+

我想使用相关子查询获得相同的结果。我无法做出＆＃34;计数＆＃34;列如上所示：

SELECT c.cust_id, c.cust_type_cd, c.city
FROM customer c
WHERE 2 = (
    SELECT COUNT(*)
    FROM account a
    WHERE a.cust_id = c.cust_id
);

结果：

+---------+--------------+---------+
| cust_id | cust_type_cd | city    |
+---------+--------------+---------+
|       2 | I            | Woburn  |
|       3 | I            | Quincy  |
|       6 | I            | Waltham |
|       8 | I            | Salem   |
|      10 | B            | Salem   |
+---------+--------------+---------+

如何获得与使用INNER JOIN的结果相同的结果并且具有＆＃34; count＆＃34;列？

Answer 1

不确定为什么要这样，但您还需要在SELECT部分中指定子查询，

SELECT c.cust_id, c.cust_type_cd, c.city, (SELECT COUNT(*)
                                              FROM account a
                                              WHERE a.cust_id = c.cust_id) AS `count`
FROM customer c
WHERE 2 = (
    SELECT COUNT(*)
    FROM account a
    WHERE a.cust_id = c.cust_id
);

相关子查询显示计数列

1 个答案: